When testing your application with libraries like Jest, Mocha, or Vitest,
it is common to use the expect
function to create assertions.
However, an assertion is only useful if it actually verifies some property of the code. For example:
expect(add(1, 2)).to.equal(2) // <- useful.
expect(add(3, 4)) // <- does not do anything.
// this does not assert anything on the value returned by strip.
expect(strip(" injuly"))
// in vitest and chai:
expect(strip(" injuly")).to.equal("injuly")
// in jest:
expect(strip(" injuly")).toStrictEqual("injuly")
// Or, if you want to test that `strip` doesn't throw:
expect(() => strip(" injuly")).to.not.throw();